Biomaterial Database

Preparation of highly efficient electrocompetent Escherichia coli using glycerol/mannitol density step centrifugation. 2011

David J Warren

Department of Medical Biochemistry at Radiumhospitalet, Oslo University Hospital, Montebello, N-0310 Oslo, Norway. david.warren@radiumhospitalet.no

Traditional protocols for preparing Escherichia coli for electroporation are laborious and often deliver highly variable transformation efficiencies. Many laboratories resort to purchasing expensive commercially prepared cells. This article describes a simple method for producing electrocompetent E. coli by centrifuging bacteria through a glycerol/mannitol density cushion. The method is rapid and replaces tedious multistep procedures with two 15-min centrifugations. Standard cloning strains consistently produce more than 8×10(9)transformants/μg pUC18, whereas the strains TG1 and LE392 display efficiencies of more than 3×10(10)/μg DNA.

UI	MeSH Term	Description	Entries
D008353	Mannitol	A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity.	(L)-Mannitol,Osmitrol,Osmofundin
D002499	Centrifugation, Density Gradient	Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Centrifugations, Density Gradient,Density Gradient Centrifugation,Density Gradient Centrifugations,Gradient Centrifugation, Density,Gradient Centrifugations, Density
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005990	Glycerol	A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, or sweetening agent.	1,2,3-Propanetriol,Glycerin,1,2,3-Trihydroxypropane,Glycerine
D018274	Electroporation	A technique in which electric pulses, in kilovolts per centimeter and of microsecond-to-millisecond duration, cause a loss of the semipermeability of CELL MEMBRANES, thus leading to ion leakage, escape of metabolites, and increased uptake by cells of drugs, molecular probes, and DNA. Depending on the dosage, the formation of openings in the cell membranes caused by the electric pulses may or may not be reversible.	Electric Field-Mediated Cell Permeabilization,Irreversible Electroporation,Reversible Electroporation,Electropermeabilisation,Electric Field Mediated Cell Permeabilization,Electroporation, Irreversible,Electroporation, Reversible